[theora] problems about theora encoding

[ogg.k.ogg.k at googlemail.com]

> If I recall correctly, the problem is that in C99 standard, all variables
> need to be declared at the beginning of a function, so the warning is
> probably caused by defining a variable in the middle of a function.

C99 allows declaration anywhere. The problem is a bug in the MSVC
code generation, which inserts code to check whether the source of
an assignment was initialized, and moans if not, even if the value is
not used afterwards. It's meant as a safety feature, I suppose, but
is complaining about things that are OK.
A quick sidestep would be to replace "sb_full=sb_full" by "sb_full=0"
in your copy of the source. This should keep MSVC happy.